Blades used in the turbine section of gas turbine engines are exposed to combustion gases, high mechanical force, and foreign object impact. This, coupled with the high operating temperature, create high levels of stress in the blade. Blade tips, blade airfoil sections, and blade platforms are particularly susceptible to stress related damages, including areas of wear and cracks. Blade tips, (also known as tip caps), include blade tip shelves (an end piece of the airfoil) and blade squealers (elevated material surrounding the blade tip). The cracks may extend from the tip of the airfoil downward toward the platform, sometimes extending past the blade shelf adjacent the blade tip.
It is known to replace worn or cracked blade squealers and blade shelves by replacing them with a new, cast blade shelf, and new squealer material. A tip portion of the blade is removed, the new blade shelf is welded to the blade, and new squealer material may be welded to the blade. Unfortunately, cracking is very often found below (toward the platform) the tip shelf, extending into the airfoil body. For example, the cracks may extend up to 30 mm below the blade tip. Portions of the cracks that extend below the bottom of the blade shelf cannot be reached with the above repair technique. As a result, blades with such cracks cannot be repaired. Consequently, there is room in the art for improved methods of repairing blade airfoils.